2. Inspection Practices forPressure VesselsDownstreamSegmentRECOMMENDED PRACTICE 572THIRD EDITION, NOVEMBER 2009 1 3.Special NotesAPI publications necessarily address problems of ageneral nature. With respect to particular circtJmstances,local,state, and federal laws and regulations should bereviewed.NeIther API nor any of APIs employees, subcontractors,consultants, commIttees, or oltler assignees make anywarranty orrepresentation, either express or implied, with respect to theaccuracy, completeness, or usefulness of theinformation containedherein, or assume any liability or responsibility for any use, orthe results of such use, of anyinformation or process disclosed inthis publication. Neither API nor any of APIs employees,subcontractors,consultants, or other assignees represent that useof this publication would not infringe upon privately ownedrights.Classified areas may vary depending on the location,conditions, equipment, and substances involved In anygivensituation. Users of this recommended practice (RP) shouldconsult with the appropriate authorities having jurisdiction.Usersof thIs RP should not rely exclusively on the Infonnation containedIn this document Sound business, scientific,engIneering, and safetyJudgment should be used In employing the Infonnation containedherein.API is not undertaking to meet the duties of employers,manufacturers, or suppliers to warn and properly train andequiptheir employees, and others exposed, conceming health and safetyrisks and precautions, nor undertaking theirobligations to complywith authorities having jurisdiction.Information concerning safetyand health risks and proper precautions with respect to part/cularmaterials andconditions should be obtained from the employer. themanufacturer or supplier of that material, or the materialsafetydatasheet.API publications may be used by anyone desiring todo so. Every effort has been made by the Institute to assuretheaccuracy and reliability of the data contained In them; however,the Institute makes no representation, warranty. orguarantee Inconnection with this publication and hereby expressly disclaims anyliability or responsibility fur loss ordamage resulting from itsuse or for the violation of any authorities having jurisdictionwith which this publication mayconflictAPI publications arepublished to facilitate the broad availability of proven. soundengineering and operatingpractices. These publications are notIntended to obviate the need for applying sound engineeringjudgmentregarding when and where these publications should beutilized. The formUlation and publication of API publicationsIs notintended In any way to inhibit anyone from using any otherpractices.Arty manufacturer marl!.ing equipment or materials inconformance with the marking requirements of an API standardissolely responsible for complying with all the applicablerequirements of that standard. API does not represent,warrant, orguarantee that such products do In fact conform to the applicableAPI standard.All rights reselVed. No part of this woric may bereproduced. translated, stored in a retrieval system, ortransmitted by any means, eleclronlc. mechanical, photocopying.recording. or othefwise. wi1hoot prior written permission from thepublisher. Contact thePublisher, API Publishing Services, 1220 Lstreet. NW, Washington. DC 20005. Copyright e 2009 AmeriClJnPetroleum Institute 4. ForewordNothing contained in any APIpublication is to be construed as granting any right, byImplication or otherwise, for themanufacture, sale, or use of anymethod, apparatus, or product covered by letters patent Neithershould anythingcontained in the publication be construed asinsuring anyone against liability for infringement of letterspatent.Shall: As used in a standard, shall" denotes a minimumrequirement In order to confoon to the specification.Should: Asused in a standard, "should" denotes a recommendation or that whichis advised but not required in orderto conform to thespecification.This document was produced under API standardizationprocedures that ensure appropriate notification andparticipation inthe developmental process and is deSignated as an API standard.Questlons concerning theinterpretatlon of the content of thispublication or comments and questions conceming the proceduresunder whichthis publication was developed shOUld be directed Inwriting to the Director of Standards, American PetroleumInstitute,1220 L Street, NW, Washington, DC 20005. Requests for permission toreproduce or translate all or any partof the material publishedherein should also be addressed to the director.Generally, APIstandards are reviewed and revised. reaffirmed, or wtthdrawn atleast every five years. A one-timeextension of up to two years maybe added to this review cycle. Status of the publication can beascertained from theAPI Standards Department, telephone (202)682-8000. A catalog of API publications and materials ispublishedannually by API, 1220 L street. NW. Washington, DC20005.Suggested revisions are invited and should be submitted tothe Standards Department. API. 1220 L Street, NW.Washington, DC20005. [email protected] " 5. ContentsPage1 Scope .... . .... ..... . ... . .... . ... . ......... . ....... . ............ ............ . . . .... . ... 12 Nonnative References. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Terms andDeftnitions ........ . . . . .. ........ . .. . ..... . ..... ..... .. ......... . ............... 23.1 Deftnitlons . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 23.2 Acronyms and Abbreviations . .. . . ........ . .. . ..... ....... " . ....... . . . .. . ........ . .. . ..... 64 Introductionto P...ssure Vessels . . ...... ............ . . . ...... . . . .... .................... . 54.1 General.. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.2Methods of ConstrucUon .. . . . .................. . . .. . .... .... . ............ . ... . . . ...... . . . 64.3 Materials ofConstruction . . . . .... . ....... .. .... . .. .. . . .. . ... .... . ..... . ............... .. . . 84.4 Internal Components andequipment .. . . ......... . .... .. . ..... . ...... . . . ....... . . ......... 74.5 Uses of Pressure Vessels .. .. . . ..... .. .. . . .. . .. . . . . ... . ... . .. . . .. . .. . . .............. 84.6 Design and Construction Standards ... . ... . .......... . ..... . . .. ..... . ......... . ..... . .... : . . 96Re sons for Inspection ............... . .. . . . .... . ................ . . . ... .. ......... . . ... 125.1 General .. . ........ .. . .. ....... .. ....... .. .......... . ...... ........... . .......... . .... . 126.2 Safety.. . . ... .. .. .. ...... . .. ......... . ....... . ........ . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 166.3 Reliability andEfficient Operation . . .. . .. . ..... ... ........ . .. . . ..... . ... . . . .. . ............ . . 166.4 RegulatoryRequirements . ... . ............. . .. . . . ... . ... . ....... .... . . .. .. . .. . .... .. .. .. .. 166 Inspection Plans ... ......... . .. .. .... . .. . ... . . .. . .... ...................... . . ... .. . .... 166.1 General .... . .... ....... .. ... .. ... . . . ... .. ...... . .............. . .... ..... . .... . ..... . ... 168.2 Inspection for Speolftc Types ofDamage . .. . . ......... . ... .. ........ .. ............ ....... . .. 168.3 Developing Inspection pr.ns . .. ................ . .. . ..... .. ..... .. .. . ......... .. .......... . 186.4 RBI . ..... . ......... . ....... . . .. . ....... .. . . . .. . .. . ... . .. . . . ....... .. . ... .... ........... 177Frequenoy and Extent of Inspection . .................... . ........ .. ....... . ............ . ..177.1General ..... . .. ...... .... ... . . ... . .... . ........ ........................ .. ...... . ... .. .. 177.2Opportunitiesfor Inspection . . .. . ... . ......... . .... . .. . ... .......... . .... . .... . .. . ........ 188Safety Precautions andPreparatory Work .... . . . ......... . ..... . ..... . ....... ............... 188.1Safety Pr808utions . . . . . . ... ..... ..... ....... . .................... . ... . .......... . ... . ..188.2Preparatory Work... .. . ..... . . . ........ . . . ........ ...... . ... . .... . ......... . ....... . ... . 199 InapectlonMethods and Limitations . ................. . .... . . . . .. . . .. ........ . ... . ....... . .. 219.1 General. . . ..... . . ...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219.2 Thickness Measurements....... ... . .... . ........ . ... ... . .... . ..... . . ..... . ... . . . ........ 229.3Externallnspeotion . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 249.4 Internallnspec;tion . . ..... . .. ... ....... . . ...... . . .. . ..... . .. . . . . .. ..................... 339.6 Special Methods of DeteotIng MechanicalDamage .. ..... . .......... . ............... .. .. . .. ..469.6Metallurgical Changes and In.sltu Analysis of Metals ...... ... ............................. . .. 468.7 Testing . . .. . . .......... . ...... . ... . . . ..... . .. . .... . . . ...... .. ... ......... . ........ . ...4710 Condition Assessment and Repair ... ... . .... . ............. . ...... . ...... . ... .. . ........ . ..6010.1 General .. .. . . . ................... . ... .... . ........ .. ...... . . . ............ . ... . .. . ... .6010.2VlsuallnspectJon . .. . . . . .. ............ . .... . ............ ................ . ....... . .......6010.3 Thickness Measurements. . ..... . ...... . ........ . . . .... . ........ .. . .......... .. ... . ..... 6110.4 Remaining LW. . ... . ... .. .... ..... . ......... . . . .......... . ... .... .. ...... . . . . . .... .. . ..6110.6 Methods of Repair ... ... .... . .. .. ..... .. ... ... . ... . ..... .. .... . . .. ..... . . . .... . ... . ....6110.6 Repair of Supporttng Vessel Equipment. ... ............................ . .. .. .. . ...... . .. .. . 63v 6.Page11 Records and Reports .... .. .. . .... ... ..... ............ .......... ... ........ .. ........... 6311.1 Records ........ ........................... . ......... . ....... ........... .... . ...... . . 5311.2 Reports ...... ..... . ......... .. .. ...... ... .... .. .................... . . ................. 63Annex A (informative) Exchangers ..... .. .. ........ .. .... . ......... ... ...... . ............. . . . . ..64Annex B (infonnatlve) Towers .......................... . . .............. .. ....... .... ........... 71Annex C (informative)Sample Record Fonns ................................... . . . .. ... . . .. .. ... 12.Figures1TYpe 316 Stainless-clad Vessel.............................. . ......... . ...................72Weld Me1a1 Surfacing ... . . . ........................ .............. .. .. . .... . .. .. ........ 83Strip-llned Vessel ... ...... .... ..... ......... . ........ . ...... .. ..... ................. .. ... 8.. Prlnclpal Strip-llnlng Methods. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 96Hex Mesh Installation forRefractory Lining .................... . . .. ..... . ........... ... . .. . 96Reinforced Refractory . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. 107Vertical Heat Exchanger . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. 118HOrizontalVessel. ............ . .. . ... . ............ .... ... ........... . ... .. ......... ..... 129Spheres ..... . . . ........................... . ... . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 1310 Horton Spheroid(Noded) ... ...... . . . ........ . ...... . ....... ... ..... ........ . ............ . 1311 ProcH_ Tower ...... . ........ ......... . .. . . ...... ... . ............. .... ........... ...... 1412 Exchangers ....... .. . .. . . ...... . .. .. ... . .... . ...... .. ...... .... . . .......... .... ...... .. 1413Exchanger Installation and Foundation ....... .. .... ..... .. .. ... ........ . .............. . .... 2614 Severe Detllrloratton ofAnchor Bolts .... . .. . . . . ...... . ....... .. ... . ................ ... . ... Z716 Method of Obtaining Vessel ProfileMeasurements .... .. . ....... .......... ...... . ... . . .......3216 . COlTOslon In Channe .. . . ............... . .... . . . ...... .. .................. . .......... 3511 Crack In Weld Seen byPT ... " ................ . ... .. . ................ .................. 3718 Hydrogen Blistering ... . . . . ............. . ...... . ..................................... . ...3819 Self-vented Hydrogen Blisters . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . .. 3920 Radiograph of S If-vented Hydrogen BUstersIn Carbon Steel ...... . .... ........ ..... ..... . .... 3921Cafalytic.....ctor Intemals--Cyclones . .. . . .. . ..... . . . ....... . .. . ... .. ... . .................. 4122 Corrosion TabMethod of Determining Metal Loss on Vessel LInings . . ......... ... .. . . ........ 4323 Strtp-tlner Deterioration .... ... . ....... . . . . . ..... .. ..... .. ... .................. ......... . 4424 Detertorated Refractory-tile Lining ... . .. . ..... .. . .. . . .................... . .............. 4526 Steps InUsing Special Equipment to Test Individual Tubes . ....... ... ....... ......... ...... .. . 49A.1Properly Rolled Tube . ....... . . .. ....... ... ... .. ... . ............. . . .............. ........ . 56A.2Tube-bundle Type of Tank Heater . ............. ........... . ..... ..... .... . ................ . 57A.3Air-cooledExchangers . . .. .. . . ...... .... ............ ... ....... . ... ...... .. .. . .. . ....... . 68AA Clean-servlce Double-plpeColis .. .............. .. ...... . . ... . . ...................... . ... . 69A.S Tank Suction Heater withEverything but Forward End Enclosed; Shell Suction Nozzle EnclosedIn Far End . ... .. ... . .. . . . .. . .. ...... .. ... .. ... ...... ........ ..... ... . ... ...... . 60A.6 Fln-ty Tubes InDouble-plpe Coli . .......... . . . ... . .. .. ...... .. .......... ........ . ...... . . 60A.7 Plate-type Exchanger . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61A.8Tubes Thinned at Bafftes ..... . .. . .... .. ........ ......... ...... .. ... . ... ... . . ... .. .... 61A.& Tubes Fretting atBam . ..... ... ... . ...................... ...... .... . . .... .... ... . . 82A.10 Eroslon-corroslon Attack at Tube Ends............... . ....... ... .. . .. ............. . .... 83A.11Heat Exchanger Parts ... . .. . ....... .................. ................ ................ 66A.12 Heat Exohanger Types ....... ... ........ .. .. .. ... . .. . . ........................... . ...... 708 .1 Typical Trays In a T0N8r. . .. .. . ....... .. ...... . ....... ......... .. ............ ........... 71B.2 Random Packing In a Tower. .. . .................. ...... ... ..... ... . . ..................... 71B.3 Tnays withDowncomers . . .. ........................ . .. . .... ....... ....... .... .. . .. . . . . . .. 72B.. Bubble Cap Flow Path . . . . .. ........ .. . .. ..... . ....... . ...... .. . .......................... 72B.5 Tow.r Stripping and RecttftcatJonSection ............. . ....... .... ..... ..... ... . ............73 7. p.ageB.6 DlskJDonut Tray . ..... ....... .. .......... ............................. ....... . ..... .... 74B.7 Ba.... TrayArranlement . . . .. .. ... ......... . . .. ..... .. .. ................ . , ... . ....... .. 76B.8 Sieve Tray ..... .. ..... .... .. ................ ..... ... ... .... ..... . ... .................. nB.9 SI ve Tray Dlstortlon . . ................................................................78B.10 Typical Trayed Tower. ... ..... ..... .. ................... . .. ....... .. ....... . .. ......... .. . 79B.11 FloatValves with Two Weights ...... ...... .. .. . .... ........................................ 80B.12 Fixed V.tves .. . ..... ... . ...................... . ..............................80B.13 Bubble Cap Vatves.................................................. . ........... "...... 81B.14 Extruded Vatves .... . . .... .. ..... . .. ... ...... .... . . .. .. .. . ... . ... .......... .... ... ... 81B.16New Floating Valve Tray .... ..... ..... ..... ... ... .. ............. .. .. . .... ... ..... . ... .. 82B.18 Caged Valves .. .. ... ........ . .. ... ...... .. ..... .. ..... .. . ........... ... .. ... . . . . .. .. . . 82B.17 Typloal Packed Tower Drawing . .. . ... ... ... .... ....... .. . .. ... ... . ...... . .. ............ . 83B.18 Random Packing, Pall Rings ..... . .... .. . ........ . .... . .. ... .. ... .. ...... . .. ........... 84B.19Structured Packing . . . ... . . . . " . ..................... ............................... 84B.20 Grid-style Packing. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 85B.21 Diagram ofRequired Scaffolding ............... ........................................... 87B.22 Hexagonal Manways.. . . . .. ......... ... . . ... . .. . .... . ... ... .. ...... .. .... . ...... ..... . 88B.23 Standing all and Water .. . ......... .. .. ... . . ......................................... ...88B.24 Trays Collapsed. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . 89B.25 Corroded Anchor Bolting ........................................................ .. . . .89B.26 Corroded Anchor Bolting ... . .. .. .. ... . ................... . ... . ... . .... . ... ... .. ... .. .. .. .90B.27 Cracked and Bulged Fireproofing ....... .... . .. .. .................. . . . ....... ..... .. ...... . 90B.28 Debris InSkirt .. .. . . .. . . . .. .......................... . ... . . ... ... . . .. ... .. . ...... . 91B.29 Preliminary InspecUon . ..... ........ . ... . . ..... .............. . . ... .. ....... ........ . . .. 91B.30 Bed Dlmage t Preliminary Inspection .. .... .. . .. ... . .... ... . ....... . . ......... . .. ...... 92B.31Manway Corrosion . . . .. . .. ....... . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 92B.32 Manway Uner Damag . ... .. . .. . . ................................. " ........... ..... .. 92B.33Corrosion on Gask t SeaUng Surface .. . ... ........................... . .................. 93B.34 Corrosion onGasket Seatfng Surface ...... ................................................ 93B.36 SurfaceCorrosion of Shell ....... . ..... .. .. . ............ .............. . . . ........ .. .... 94B.38 Inspection From theBottom Head........................................................ 96B.37InspecUon of Packing via Riser ........................ .. . .. . ........ ... . . . . . . . .. ..... .. 96B.38 Dernister BypassDeposits .. .. .. ... ........ . ................................ .. ... . . ..... 95B.39 Fouled Demtster Pads ... .. . ..... ....................................................... 96B.4OFaulty Deml$ter InstallaUon .... ....... . . ............. . . ......... ... .. . . .......... . .... 988 .1 Preferential Corrosionof the Head to Shell Weld ......... .. . .. .. .. ... .. ............... . .... .. 97B.42 Head Seam prer.rential Corrosion . ..... .. .. .. .. ................ . .................... 97B.43Preferential Corrosion of the Sh II .. .......... ... ...... ......... ............ . ... .. ... . . .. 98B.44 PerforationDegradation . ..... .. .. . ..... .. ............ .. ... ....... .............. . ...... 98B.46 Chimney Tray Deformation at Draw Sump... . ... . . ....... .. ... .. ...... ....... .. . ........ .. .98B.46 Fouled Troughs on Box and Trough Distributor................. . ........ . . . ...... . ...... . . 99B.47Obstructed Pipe Dlstrtbutor Perforations . ....... .................................... .. ..... 998.48 Box and Troughs. ... .. . . . . . ..... .......... ... .. .. ... ................................... 99B.49 Hit the Washers, Not theBolts . ................. . ... .. . "............................... 100B.5O Random Packing on ValveTray . . .. ............ . . ...... .. ....... . ........ .. .. ....... . . .... 100B.S1 Bed Limiter Above Random Packing . .... . ....... ... ..... .. ........ . .. . ....... . . .. . .. 101B.152Dislodged Packing ... . . ... .. . .... ... ..... .... ...... ........... . .. .. . ................. 101B.63 Damaged Packing SupportGrid ..........................................................102B.64 Support Grid from Below . .. . . ... .. .. .... . . ....................... .. . . . ............... 102B.65 CorrosionInside Sightglass Nozzle .. ................ . ..... ...... ............ . . .. . . ...... 103B.56 Bottom Head, Vortex Breaker, andDebris .................. .. ... . ................ .... ......103B.67 Fouled Grid-type Packing .. . ............................................................. 104vii8. PageB.68 Cracked Plug Weld .. ... . . .. .. .. .. .... . . . .... . " . . . .. . .. . .. . . .. . .. .. .. ... . .. . . .... .104B.69 Stainless Steel Donut CladdIng Breech . . . . .. ..... . ... ... ... .. .. .. . ... .. . . . . .. .... .. .. . 106B.60Cladding Bl88Ch at Gouges In 8ottom Head . .. . .. . . .. . .. . ....... .... .. . . .. . ... .. .. . . .. . . 105B.61 410 StainlessSteel Clad to Carbon Steel Interface W.,d . ... .. ... . .. . . ..... . . .. . .. ... . .. ... ... 106B.62 Suppl mental UT Martdngs... . .. .. . . . . . . . .. . .. . .... . . ........ . .. .. .. .... . . . .. .. . . . . . . 106B.63 Cracking at Tray Support RingWeld .. . .... . ... . . . . .... . . .. .... . . .. . . . .. ..... . . ... .. . .. . . . 107B.64 WFMPT Dlscovered Cracking .. .. ... . ... ..... . . . . .. .. .... .. . ...... . . ... .. .. . ........ 108B.65 Supplemental NOE May be Needed . ... ... .. ... . ..... .. ... .. ... . ... .. .... .. . .. ..... . ... . . . . 1088.66Areas of Chemical Activity . . .. . .. . . . . .. ....... .. . ..... . ..... . .. . . ......... . .......... 109B.87 Areas ofActivity .. ... . ... . .............. . ..... . . . . .. ... . .... . . .. .. .. . . . . . . .. . .. . .. .. .. 109B.68 HardwareCOfToslon ........ . ... . .... ...... .. . ... . . . .... . . . ... .. . .. .. . . .. .. . . . . .. .... 1108 .69 Stuok ValvesAlways Open .. . .. . ... .... . .. .. ... . . .. . .. . . ......... .... .. . . . . . .. .... . ... 110B.70 Clean Square-edgedPerforation .. .... ..... ... ..... ... .......... . ... ..... .. ., ....... . . .... 1118.71 Valye Fretting . . . . ... . ..... . . .. . . . .... . . . ...... .. ... .. . . ..... .. . . .... ......... .. .. . . . 111B.72 Slotting from Below. . . . . . . . .... .. .. . . . . .. . . .. .. . . . . . ... . ... . . . . . . .. .. . ... ...... . ... . .. 1118.73 Valye Leg and PerforationInspection . . . . . ... ..... . . . . ... .. .......... . . ...... . .. ... . ... . . .. 11208.74 Indentation Valves . .. . .. . ... .. . . . ... . . . . .. .... . ........ . .... . . . . . . ... .. .... ..... 1128 .76 New Caged Valves with Dimples . ... .. .. ..... . ..... . .. . .. . . . .. . ...... ... . ..... . ... . " . ... 113B .76 New Caged Vatv Cage Tabs ... . ....... . .. . .. . . ...... . .. . .... .... . . .. . . . .... . .. . ......... 113B.77Small Fixed Valves . . . .. .. . .. .. . . . ... . . .. .. . . .... ... .. ... . . . . .. . .. . ... . ... .. .. . . 114B.78 FixedVatves Lateral Vapor Directional Flow . . .. . . . . .. " . . . .... ........ . , .... ...... ..... .. .. 114B.79 Removabl. FixedValves Reduce Fouling ...... ... . . . . . . . ..... ... .... ..... ... .. . ... ..... . .. 116B.80 Removable Fixed Valves TrayDamage . .. ...... . . .. . . . .... .. .. . .... . ... . . . . ... ... .... . ... . 1158.81 Bubble Caps on Stepped Trays . .. . .... ... . .. ... .. ... . ......... . . ... . .. .. . ...... . ..... . 116B.82 Fibrous Deposits and Fouling Under Bubble Caps .. ...... . ....... .. ...... . ... .. .. . ...... . . .. 116B.83 TrayDeck Should be Scraped Clean ..... . . . . ... .. . . .. .... .. ..... .. .. .. . ..... .. . ... . .. . .. . 117B.84 Tray FatigueCracking ... . . . .. . .. . .. . . . . . ..... . .. .. ..... ..... . .. . . ...... . . .. ...... .. . . 11 7B.86Llght-to-moderate Well CorrosIon . .. ... .. .. .. . . . .. .. ..... . .. . .. .. . .... . .. . ... . .. .... . .. . .. 118B.86 Looseand MissIng Hardware Fallur. . .. .... . ..... ... . . . ... .. .... ... .. .... .... .... . .. . . . . . . 1188.87 Oowncomer andSeal Pan Clamps Loose .. ..... . .. .. ... . ... . . ... . .. . ... . . . . . .... . ... . 119B.88 DowncOiner Clamp Loose . .. . . .. . . . .. . .. . . . . ... . .. ... ... .... ..... ... .. ......... . .. . . . . . 119B.89 Tray Support Ring Corroded to Failure. .... . . .. ... .. .. .... . . .. ...... ... . . ... . .. . ... . ..... .. 120B.90 Depostts Adjacent to Shell are on Ring . . ...... .... .. . . . . ..... ...... ... ......... ... .. ...... 120B.91Shell Corroded to Half Will Adjacent Top Three Rings . . ... ... .... .... ..... ... ..... . . . . .. . .. 121B.92 Support RingGrooving . . .. ... . .. ... ...... .... . .. ..... ... ... . . ....... . ... . . . . . . . . 121B.93 Cracking of Ring AttachmentWeld . ........ . . ..... .. ..... .. .. .. . .... . . .. ... .. .. . .. .. .... .. 1218.94 Tray Support Ring Butt Weld Cracking.......... . . .. ..... . . . .. .. .... . .... . .. . ....... .. ..... 1228.96 Breechlng of the S al Wold . . . ... ... . . .. . .. .. ... . ... .. ... ... .... . ....... ... .... .. .. . . .. 122B.96 Shadowfng Inside the Downcomer . . . . ...... ... .. ... . . ... .. ... . . ..... . .. . . . .. . .... . .. . 1230 .97 Shadow theDowncomer Shell Every Tray . ...... . ..... . ...... ... ..... . .. ... .. .. .. .. . . . . ... . 123 9. Inspection Practices forPressure Vessels1 ScopeThis recommended practice (RP) covers theinspection of pressure vessels. It includes a description of thevarioustypes of pressure vessels (including pressure vessels wittla design pressure below 15 psi g) and the standards fortheircons1ruction and maintenance. This RP also Includes reasons forInspectlon. causes of deterioration, frequencyand methods ofinspection, methods of repair, and preparation of records andreports. Safe operation is emphasizedwithin this RP.2 NonnativeReferencesThe following referenced documents are indispensable forthe application of this document For dated references,only theedition cited applies. For undated references, the latest editionof the referenced document (including anyamendments) applies.API510, Pressure Vessel Inspection Code: In-service Inspection,Rating, Repair. and AlterationAPI Recommended Practice 571. DamageMechanisms Affecting Fixed Equipment in the Refining industryAPIReoommended Practice 574, Inspection Practices for PipIng SystemComponentsAPI Recommended Practice ST5,Guidelines and Methods forInspection of Exisling Atmospheric and Low-pressureStorage TanksAPIRecommended Practice 576, Inspection of Pressure-RelievingDevicesAPI Recommended Practice 577, Welding Inspection andMetallurgyAPI 579-1/ASME FF5-1 , Fitness-For-Service API Standard660, Shell-and-Tube Heat ExchangersAPI Standard 661, Air-CooledHeat Exchangers (or General Refinery ServiceAPI RecommendedPractice 945, AvoIdIng Environmental CrackJng In Amine UnitsAPiPublication 2214, Spark Ignition Properties of Hand ToolsAPIPublication 221 7A, Guidelines for Safe Worle in Inert ConfinedSpaces In the Petroleum and PetrochemicalIndustriesASME Boiler andPressure Vessel Code (BPVC) , Section VIII; Pressure VesselsASMEPCC-2, Repair of Pressure Equipment and PipingNB-23 2, NationalBoard Inspection CodeTEMA 3, Standards of Tubular ExchangerManufacturers Associationt ASME International, 3 PariIllPetion ofdlscovery M)t1c:.Hand cleanlng of those areas not adequately cleaned via steam outand chemical deanlng isfrequently required due to the oompIexIty ofthe Internal oonflgurations.Us!ng the equipment elevaHon drawing,manway covers; manway gasket aurfaces end manway bore Internal. . .- . should be labeled and Inspectod. Debris I"Skirt Figure B.28Debris In Sldrt F1ti1Ufe B.2I--PreUmlnary InspKtion 100. 92 API RDPRAcnce 572 Figure B.3O--8ed Damage at Preliminary InspectionFigure B.31-Manway CorrosionFigure B.32--Manway Uner Damage 101.INSPECTION PAAcncEs FOR PRESSURE VESSB.S OJ. ... _1M ........ II c__ O k.1 5.1111"1 SlI rt . C. Figure B.33--Corroslon on GasketSeating SurfaceCracked Plug welds Manway liner damage covered byBlower at Inltlallnspeetlon Figure B.34-Corroalon on Gasket SeatingSurface 102. .API REcot&IENXo PR.t.cnce 572Very Light ,ofShellCo rrosion due t o conden tionFigure 8.35--$urfaet ColTOllon ofShellPatticUar care should be taken with nned manways andCOY8IS.Craddng aM bulging at liner plug welds and oonoequendalootrOSion bahlod the _ . oonoded or damaged _surfaces and/orInternal COOOI!IIon of the bore or stagnant areas should bedfsoovered prior to installation of ventilationequipmenl8.4.5Viluallnlpection of Packed TowersSA.5.1 GeneralPacked towers havetwo basic sets of oonditions; packing removed and packing In place.If pecking Is not removed, alimited or partial visual Inspection Isthe most whim can be performed. Under these conditions, the degreeofInspection Is a variable, cootrolled by the degree of disassembfyof the internals, the type of packing and the amountof accesspennitted by operations.8 .... 5.2 PKked Towel1l Packing InPlaceInspection of a tower with packing in place Is limited to thetop and bottom heads, the adjacent shell, and those otherportionsof the pressure retaining boundary that are aocessible, theaccessible nozzle bores, the top and bottomsurface pactilg and theInternals (FIgure B.36 and Agura B.37 demorsbate the Nmitadvisibility of a paddng In placeInspectionlNormal visual inspectionand quantificetlon of the surface texture and 00IT0Si0n present onthe top head and shellcourse may be suppktmentad with UT thicknessmeasurements. Thickness measlX8ments fA susceptible areas Ofareasof vtslble impingement shoukt be taken in oonjuncllon with thevisual Inspection throughout the tcM may lead to ",.,apilation ofeotnl8Ive Hquids from the IMHf1ead vapors. 103. .Inspection ofp.Kklngfrom tM bottom heMHo touUng or dMnage. .FIgureB.3&--lnapectfon From the Bottom Head Inspection of p.cklngvi. Or1flc. PI.te ChimneyFigure B.37-1nspection of Packing vMIRfMrFigunt 8.38--Otmlster Bypass Deposftl 104. . Figure B.39-FouledDemlster Pads0 ............. " ___.... .............In......preb..... ss Figure B.4O--Faulty Demister Installationtn thecase of contactor towers with random packing Installed, removal ofthe packing bed Is preferred. Vibnltion of thepacklng against theshell can cause or accelerate erosionloorroslon as contaminantsfrom the process stream build-up In the solvent or aaubbingmedia.All vlsible portions of the towsr weld seams should beInspected for cracking, wear, pitting and preferential00fT0Si0n ofthe heat affected zone wald or shell (Figure B.41 through FIgUreB.43 &how examples of thesedamage mechanisms).When inspectingthe Internals of a packed tower with the Internals still Installed,access can be severely limited. Asmany perforations of the Internalpiping and the distribution system as posstbIe shoukJ be inspected.All perforationsshould have appropriate shaping and square cutedges (see FIgUre 8.44)."Out-of-round" and loss of edge profile 00Internal distributor perforations are indicative of wear orcorrosion. Note anyvisible obstructions of perf01 atlons ordistribution piping for oorredIon.ChImney or ooIlector traysfrequently require supplemental cleaning, since they are designedto hold Aquid. Properdeanlng of this area Is requillld to allowdlscov9l) of oorroalon or pitting of the tray dad: and shell. Drawsumps, If- . shcx.Ol be particularly wei cleaned 10 aIow dosevisual inspection of the dmw nozzle atlactvnent weld andthe nazzjebore for COfTOSion. 105. ., F1gu... B.41-Prefe1enUai CorrosJon ofthe Hud to Shell WeldFigure B.42-Head Seam PreferentialConosionChImney trays are someUmes subjected to cyclic pressure dueto var1atlons In vapor now and cyclic lIQuid loads.CtWnneys shouldbe dlecked for distortion (see Figure B.45) as well as aacIOOg.Seal welded chlrmey trays shouldbe inspected for aackIng at thebase and vertical edges of the chimneys, at the deck seam sealwelds and at the rngseal welds.Box and trough distributors, whereinstalled, should be checked for ntemal debris, obstruction of anyperforations andfor any distortion or damage to drip pointenhancement devices (where Installed). 88e Figure B.46 throughFiguraB.48. Trough. wtlk;h .... holding liquid probably haveobstruded peIforations.1QttI1ng haldliare" on IntemalB is the mostcoovnon method of ensuring tightness, however, hardwarewhichappears tight when "rattled" may be held In place by a singleItv"ead, with an exposed threadrlg evenly degradedwhere In contactwith the process ftulds. This Is fairly common on the refluxdistribution system of amine towers.Slriklng several nutslboltssIwpIy at an angle with the Inspection hammer should reveal thiscondition (see FIguraB.49). In 81 other cases, where halVNare Isactually hit with the Inspection hanmer, hitting the washer Isbest. The 106. . Figure B.oU-Preferential Corrosion of the ShellFigure B.44--Perforaflon Degradation ,f2DA-2Ot1M.lnF.-.ctJon.torFigura B.45--Chlmney Tray Deformation at Draw Sump107. INSPECTlOH PlW:ncEs fOR PFlUSURE VEssa.s..Figure B .ouledTrough, on Box and Trough DI,b1butor FIgura B.Aa-80x and Troughs108. 100Agu,.. B.49--Htt the Washers, Not the Balta FigureB.5O--Random Packing on Vlilve Traytorque values on tower hardwareare relatively low, and loosening may result from hammer blows.Tower attachmentsshould also be SOlIldecI with an Inspection hammerto ensure attachment welds are not Cf8Cked.In all cases, thedistance from !he padting to the bed Imiter should be 19COfded.Ensure recon:ting of this Infonnationprior to the removal 01 thebed limiter If the bed limiter is to be removed for access. Bedlimiter Integrity and hardwareshould be dIecKed, as well as chedISO 9001 RegistrationPhone: 202-682-851 6> ISO/ TS 29001Registration Fax: 202-962-473 9> ISO 1400 1 Reg istrat ionEmail:[email protected] org> API Spec Ql RegistrationPhone: 202-962-4791APIPETROTEAM (TRAINING,Fax:202-682-8070 EDUCATION ANDMEETINGS)Email:certiicationapi.orgPhone: 202-682-8195 Fax:202-682-8222API PERFORATOR DESIGNEmail:petroteamapi.orgREGISTRATION PROGRAMPhone: 202682-8490APIUNIVERSITyTMFax: 202-682-8070Phone: 202-682-8195Email:[email protected]: 202-682-8222 Email: traininapi.orgAPITRAINING PROVIDERCERTIFICATION PROGRAMCheck out the API PublicationsPrograms,(API TPCPTM) and Services Catalog online atwww.api.org.Phone: 202-682-8490Fax: 202682-8070Email:[email protected] rg-f1ill Copojright 2008 - API, oll ,!ghu resefVIQR.API Spec 01. API TPCP. ICP, API Urwer31ty and the API logo .....lIlthQr In!d,,,",,, or reglstetW of APl in the Unlilld StatesancIor other cou ntr ies. 146. 1220 L Street. 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